let agent = navigator.userAgent.toLowerCase();        //检测是否是ios
let iLastTouch = null;                                //缓存上一次tap的时间
if (agent.indexOf('iphone') >= 0 || agent.indexOf('ipad') >= 0)
{
  document.body.addEventListener('touchend', function(event)
  {
    let iNow = new Date()
      .getTime();
    iLastTouch = iLastTouch || iNow + 1 ;
    let delta = iNow - iLastTouch;
    if (delta < 500 && delta > 0)
    {
      event.preventDefault();
      return false;
    }
    iLastTouch = iNow;
  }, false);
}
